Method for freeing stuck drill pipe

Abstract

This invention relates to a valve assembly (drawing) which will hereafter be referred to as drill pipe freer, comprising a metal ball, hollow in the center, and of such design that it will float in liquid, or a floating solid plastic ball of such design and hardness to withstand the pressures to be encountered during operation of the invention, and a specially designed valve body with seat for the metal or plastic ball. The said valve body will be pumped down inside the string of drill pipe and collars within the well bore to anchor at drilling bit at lower end of drill pipe string. The said metal or plastic ball is then pumped down to seat itself within the said valve body seat, closing off the mud circulation (drilling fluid) which normally flows through drill pipe and out drilling bit and back up annulus of well bore. This sudden cessation of downward flow of drilling fluid will provide a water hammer blow to dislodge drill pipe lodged in off-bottom positions within well bore.

I claim: 
     
       1. A method for dislodging a stuck-off-bottom drill string, including a drill bit and drill pipe, comprising the steps of: (a) pumping a valve body down inside the drill string to anchor at or above the drill bit in a position to receive a spherical member for sealing action, said valve body having means for diverting drilling fluid into means for expanding its diameter upon receiving said spherical member, thereby sealing itself against the inside of the drill string and consequently blocking off flow in the drill string; and   (b) pumping said spherical member down the drill string to seat in said valve body, thereby causing said body to expand and block the flow of drilling fluid, resulting in a hammer-like impetus to force the drill string down and out of the stuck position.   
     
     
       2. A method as in claim 1 wherein said spherical member is buoyed by the drilling fluid upon cessation of flow, further including the step of again pumping the spherical member down to seat in the valve body to repeat the said impetus. 
     
     
       3. A method as in claim 1 wherein said means for expanding the diameter of the valve body includes means for diverting the drilling fluid, and an expandible packer for receiving the diverted fluid, whereby the packer causes the sealing action against the inside of the drill string.